The present study explores the relationship between school principals' beliefs, attitudes, and knowledge with their practices concerning the education of students with disabilities, shedding light on their pivotal role in fostering inclusive education. Data were obtained through a validated questionnaire tailored for the Greek educational context, administered electronically to a representative stratified sample comprising 582 school principals from 334 primary and 248 secondary schools in Greece. Correlation and hierarchical multiple regression analyses were conducted, revealing intricate and multi-dimensional relationships among the variables under investigation. The findings suggest a significant correlation between school principals' knowledge and their beliefs, attitudes, and subsequent practices related to the education of students with disabilities, although further exploration is warranted to elucidate the nature of this relationship. A nuanced understanding of the interplay between school principals' knowledge, beliefs, attitudes, and practices regarding the education of students with disabilities holds potential to further the goals of inclusive education.